Dental operative instrument



April 3, 1934. F. J. BRONNER 1,953,584

DENTAL OPERATIVE INSTRUMENT Filed Sept. 17, 1931 FICB': J

Patented Apr. 3, 1934 UiE STATES FFEE Finn J. Brenner, New

York, N. Y., assignor to The S. S. White Dental Manufacturing Company, a corporation of Pennsylvania Application September 17, 1931, Serial No. 563,299

1 Claim.

ly invention relates particularly to that class of dental operative instruments that comprises a long slender handle having a relatively short tapering shank terminating in a blade or other suitable device best adapted to cutting, scraping or otherwise subjecting to the desired treatment the object being operated upon.

It is a well known mechanical principle that the operating tool end of such an instrument should be as near as practical to the axial or medial plane of the handle to obtain the best working conditions when said instrument is being thrust forward or drawn backward in the direction of the axis of said handle while pressure is exerted in the direction of the actuating cutting edge, point or surface, and it has been long recognized that if said tool end or cutting edge be brought back of the axis the instrument will not wobble. This is clearly set forth in The Dental Cosmos, August 1905, page 24, of the advertising section.

It has been further suggested that the point of the instrument should be set back by bending the shank of the instrument so that the Working position of the actuating cutting edge, point or surface shall be disposed in a plane which intersects the point of pressure of the finger and the point of rest of the thumb of the operator on the handle and thereby so balance the instrument that it will keep its cutting edge squarely seated against the surface being operated upon and will not tend to turn or twist in the operators hand while being thus used.

It will be obvious that when the operating point, edge or surface of an operative instrument having a strai ht handle is brought back of the axial plane of the handle sufficiently far as to be in a plane passing through the points of pressure and rest on the upper and lower surfaces of said handle, that said plane will be disposed at an angle to the axis of the handle and that by reason of this angular relation of such a plane to the axis of a straight handled instrument any change in position of the points of power or fulcrum tends to throw the instrument out of working balance.

The principal objects of my invention are to provide an operative instrument that will not be unbalanced by a change in longitudinal position of the points of power and fulcrum, but which affords a plurality of points of pressure and rest disposed in parallel surfaces which as nearly approximates the medial longitudinal plane of the handle as practical without causing undue distortion or deflection of the tool shank so that the cutting edge, point, or actuating surface of said tool may be disposed near to the axis of the handle and will tend to seat itself upon the edge operated upon without its handle tending to turn or twist in the hand of the operator, thus affording an instrument in which all directional working pressures will best harmonize.

Gther objects of my invention are to provide an operative instrument having in its handle a double bend providing an offset forward. region and a medial obliquely disposed region affording an abutment against which the operators thumb and fingers may engage to insure a firm grip of said handle in the operators hand and thereby facilitate a positive thrust or draw of the instrument in its actuation.

My invention comprehends an operative instrument that affords a substantial range of lengthwise change of position of power and fulcrum application of the operators fingers and thumb without altering the operating balance of the instrument.

Specifically stated, the form of my invention as hereinafter described comprises an operative instrument provided with a tool point or blade and having in its handle, slightly forward of its medial region, a double bend so formed that the plane intersecting the point or blade will pass entirely through and emerge from the opposite end of said handle and be disposed parallel with the upper and lower surfaces of the handle in slightly spaced relation to the upper forward surface and correspondingly spaced relation to the lower rearward surface of said handle.

My invention also includes all of the various novel features of construction and arrangement as hereinafter more definitely specified.

In the accompanying drawing, Figure 1 is a side elevational View of an operative instrument constructed in accordance with my invention, shown held in the hand of the operator and having its cutting edge in actuating position with respect to a tooth being operated upon; Fig. 2 is a side elevational View of the operative instru ment per se shown in Fig. l, and having indicated thereon, in dot and dash lines, the medial plane and, in dash lines, the axes of the handle portions for convenience of illustration; Fig. 3 is a top plan View of the operative instrument shown in Figs. 1 and 2; and Fig. 4 is a cross-sectional view taken on the line 44 in Fig. 2 indicating how the finger envelops the handle pressure portion in action.

In said figures, the operative instrument which I have chosen to illustrate comprises the handle 1, shank 2 and the terminal tool form 3 which may be an operative surface, a point or cutting edge of suitable contour, said handle being shown hexagonal, but obviously may be otherwise polygonal or cylindrical, as desired.

The instrument illustrated is arranged to be held in the hand of the operator, as shown in Fig. 1, and is provided with the transverse cutting edge 3 having the breadth indicated in Fig. 3 and designed for the purpose of the cutting or scraping operation on an artificial tooth 5. Said instrument has its handle provided with the opposite double bends 6 and 7 near its longitudinal medial region but preferably disposed slightly forward thereof affording an obliquely disposed portion 9 joining the forwardly and rearwardly directed end portions 10 and 11 of said handle.

As best shown in Fig. 2, the forward upper surface 12 serving as a pressure surface of the handle against which the operators fingers bear in exerting power, and the rearward end surface 13 serving as the rest or fulcrum surface which is supported by the operators thumb, are disposed in parallel planes equally spaced from the medial plane 15 of the handle which intersects the op erative surface, point or cutting edge 3, it being noted that this medial plane 15 is disposed be- T tween the axis 16 of the forward end portion 10 of the handle 1 and the axis 17 of the rearward end portion 11 of said handle.

My invention is advantageous in that by reason of the bend in the handle which provides straight surfaces for power and support application and which lie in relatively spaced parallel relation to a medial plane passing through the cutting edge and extending through said handle intermediate of said surfaces and the axes of the relatively on?- set portions, a lengthwise change in position of power and rest application is afforded without altering its tendency to maintain balance, and by virtue of the enveloping or embracing of the tool handle by the fleshy part of the fingers and thumb said surfaces may be so spaced from said medial plane as to permit the cutting edge to closely approaoh'the handle axis and thereby be positioned as near as practical to the ideal line of thrust and draw.

I do not desire to limit my invention to the precise details of construction and arrangement as herein set forth, as it is obvious that various modifications may be made therein without departing from the essential features of my invention as defined in the appended claim.

Having thus described my invention, I claim:

An operative instrument terminating in a blade or point and having its handle provided with an oifset forward region affording an elongated straight pressure surface for the operators fingers, and an elongated rest surface for the operators thumb, said blade or point being disposed in a plane intermediate of said pressure and rest surfaces and parallel therewith.

FINN J. BRONNER. 

